So that's an example of how removing codification (reaction rolls) hurts player power. I think you agree? 3E did take away some codification. So did 4E - I made the example of the stunt adjudication "rules" in 4E, which basically amount to "ask the DM, he'll decide how hard", which is a step back from 3E's codification, which attempts to pretty much lay out what you'd roll in various situations.
I think one other thing to consider is, unless players had pushed for more power, and been given it, would have seen the move towards the beneficent "DM as fair and fan" model, or would we have seen a continuation of the adversarial model? A model which was explicitly argued for sometimes in older stuff - Gygax's "how to DM" book basically argues for adversarial DMing (it's a terrible, terrible book and made me lose a lot of respect for him for a long time). Of course then later you find out EGG did not practice ANY of what he preached in that book...
I mean, maybe that's the wrong question because even from the early days, games like Traveller gave a lot more codified power to PCs (not to mention superhero games) - I think maybe a better question is, if D&D hadn't gradually granted players more codified power, would it still be around meaningfully (i.e. not some game on the decline, perhaps even half-forgotten)? I'd say no. If 3E hadn't moved hard in the direction of codification, I expect it would died out among under-40s, and we'd all be speaking Russian... errr, I mean we'd all be playing stat+skill dicepool games like WoD/Shadowrun as the "mainstream" of RPGs. Maybe someone would revive D&D with new, stat+skill-based rules...